Max Compression on pump gas?

Rob:

I have T/A Stage 1 SE's.

Since Fall of 2007

About 46 passes on it since then, plus street miles.

Yes, 93 octane Shell.

No wide band wired into car, have checked it at wot on the street. Depending on temps, anywhere from 12.2 @ 90*12.2 to around 12.7 @ 50* a little on the fat side. However, I just installed a new carb and am going through the whole process all over again. Gonna try to lean it out a touch to 12.7 to 13.0

I hope this helps.

John

 

It does, thank you.

 

Bob,
I ran 10.5:1 with iron heads and a TA 413. We can still get 93 octane here in MI. The 413 is very tolerant of higher compression.

As far as power brakes go with a 413, mine sucked. Vac can did not help much either. Put on a hydroboost and now have great brakes. Just letting you know.

 

Not to hi-jack the thread but what's with low vacuum and a 413, it only has 13 degrees of overlap, are you guys sure about your compression ratios? The old KB 113 ran awfully good and has the same overlap but a little less intake duration and a little more exhaust duration. That cam was used for lower compression engines and ran great and had enough vac for brakes.

 

Just what I see on my motor and from discussions with others. I can never pull more than 11 inches on idle and only 16 or 17 at cruise. Some say that should be enough but did not work for me. In my opinion you need 17 inches of vacuum at idle to have good power brakes. Again this is just what I see on my setup and it only got worse with the Procharger.

The point was I wanted Bob to know that this could be an issue for him.

 

Got it, my engine pulls around 11 at idle and my power brakes work great (imho). I'm sure we'll cross paths somewhere, it would be interesting to have you drive my car and see what you think of my brakes.

 

Doug do you think if you advanced the cam more the vacuum would have been enough? How big of a booster do you run?I am manual breaks so I've never worried about vacuum.Just looking for info.
Jamie

 

I thought mine were OK (but not that great) Then put on the supercharger, did not help a bit:grin: Once I got the hydroboost dialed in there is no going back, great feel and power. It may well be that there could be improvements by putting in a new vac booster. Still won't match the hydroboost IMO.

I know that some can get the power boosters to work at low vac, some can't. I know on my sisters 65 Mustang 14 inches at idle is still not great.

As far as advancing the cam did not want to go there with boost. I do not know if that would help. Buy the way my motor is fresh from a rebuild and has about 1000 miles on it.

Back to the original question. Iron heads, ta 413, and 10.5:1 with 93 octane is no problem. You can run another .5 easy with Al heads.

Rob,
Do you get up for the Frankenmuth show. I plan on being there all weekend and on the street Friday night.

 

I doubt it, when is the show?

 

For "around town" use, my timing is at 32. Race time it gets advanced.

 

I put the 464 together with a lot of compression for pump gas(11.56:1 with 93/94 octane) using .030 gaskets, thinking I'd swap a thicker gasket in there if I had to. But I was surprised that not only did it not ping on the dyno, it didn't on the street also. I was using a 4000 stall convertor, and am now going with a higher stall because the power band is higher than I originally planned. :beers2:

Non the less, it drove around on the street :3gears: with no overheating or detonation problems. Even when I put the convertor clutch on (4L80E trans) and have no slippage on the highway, it still didn't ping unless I lugged it. Mike at TA seemed to think I'd have no problem with the compression ratio and he was right, I'd suggest anyone to get him to run whatever combos you want to use through his program, he seems to enjoy toying with all the options.:Brow:

 

We put the Vacumn canister on this GS with P/D/Brakes, an AMP 464 motor, 9.6-1 CR, and the 413 cam.
12.30's with a 3.23 (for now) Olds 8.5" rear end, and those 28" MickeyT DR's thru the tailpipes.
Works well in my buddy's GS, but could use a linelock to be less "iffy" at the starting line :3gears:

 

Did not like "iffy."